While there can be stomach sounds when a rabbit drinks water, it is very different from the loud gurgling that comes from a digestive upset and gas buildup. Pellets could very well be causing your buns current digestive problems. In fact, I've more often found the sugars and starches in pellets to cause more issues than leafy veg. Some rabbits can also have a negative reaction to meds as well. Really the only way to find out what might be causing the problem would be to eliminate foods and see if she improves. If you think it is the pellets you can try several days with those cut out to see if there's improvement. Or you could cut out veg and pellets and just feed unlimited grass hay. Then when her digestive system has stabilized and is back to normal for several days to a week at least, then you can start adding things back in one at a time, and starting with small amounts and gradually increasing each day, carefully watching for any digestive problems. If you continue to see problems with both veg and pellets cut out, it could be the meds contributing or possibly the type of hay you are feeding. Generally a non grain grass hay doesn't usually cause any issues for rabbits, but there are some rabbits that are sensitive to hay types.
Her being a young rabbit may have something to do with it, as they digest sugars and carbs differently than adult rabbits. Also some rabbits can become sensitive to certain foods. It may be she was either getting too many pellets, or a certain veg upset her digestion, and now that the bacterial balance is thrown off, she is just extra sensitive. You just need to find the food that is causing the gas, and limit the amount of sugars and carbs that she is getting(including the ones in pellets), to give her digestive microflora a chance to return to normal.
